The present invention relates to a novel multipurpose basic apparatus for treating powders. More particularly, the invention relates to a compact, fundamental, multipurpose basic apparatus for treating powders which is applicable to various powder treatments such as spray drying, fluidized bed drying and granulation and fluidized bed continuous drying.
Spray drying comprises instantaneously drying liquid materials such as solutions and suspensions by atomizing them. This method is advantageous in that the material to be dried is not subjected to a high temperature which causes the properties of the material to be modified by heat, in that condensation, filtration and separation processes can be omitted, and in that the material can be dried within a short period of time. Accordingly, spray drying has been put to practical use in various drug and food industries.
Fluidized bed drying and granulation comprises drying wet powder and granulating the dried powder by using a fluidized bed. Fluidized bed drying may be carried out by a batchwise or continuous process. In this method, the granules to be dried or the mass thereof are dried while being maintained in a dynamic suspended state by the action of hot air. This method is advantageous in that uniform drying can be achieved within a short period of time at a relatively low temperature. Further, the fluidized bed granulation comprises spraying a solution containing a binder onto particles in fluidized state to agglomerate them into granules. This method is advantageous in that it produces a higher yield than other granulating methods, in that the degree of contamination is less, and in that the operational time is shorter.
In the case where these powder treatments are carried out on a small scale for a purpose such as experimental research, production of a small quantity of product, or pilot plant tests, it is desirable that a small-scale apparatus be used. However, compact small-scale apparatuses suitable for carrying out these tests are scarce. Accordingly, when the above mentioned tests are conducted by using conventional apparatuses, the installation thereof requires an excessively large space, and the cost of the experimental materials becomes high. Furthermore, a long period of time is required for testing.
In order to overcome the above described problems, Japanese Patent Laid-open No. 72768/1976, for example, proposes a compact spray drying apparatus. However, this apparatus is applicable only to spray drying. That is, if other powder treatments, particularly those which are based on different principles, are to be carried out, different treating apparatus are required, which inevitably results in an increase in the cost and space for installation.